Carburetor



Dec. 31, 1935. F. H, HEITGER CARBURETOR Original Filed Deo. 2l, 1928 5 Sheets-Sheet l Dec. 31, 1935. F, H, HElTGER l i i 2,025,860

CARBURETOR Original Filed Dec. 2l, 1928 3 Sheets-Sheet 2 Dec. 31, 1935. F. H. HEITGER CARBURETOR Original Filed Dec. 2l, 1928 3 Sheets-Sheet 3 [lll/111117110v Patented Dec. 31, 1935 2,025,860 CARBURETOR Frank E. Heitger, Flint, Mich.; Mattie G. Heitger, Flint, Mich., administratrix of said Frank H. Heitger, deceased, assigner to'Bendix Products Corporation, South Bend, Ind., a corporation of Indiana Application December 21, 1928, Serial No. 327,674

Renewed June 26, 1935 9 Claims.

This invention relates to certain new and useful improvements in carburetors and more 'particularly to carburetors especially adapted to be used on motor vehicles propelled by internal combustion engines, the object being to provide a carburetor with a by-pass for feeding auxiliary air having a suction operated valve in connection with a manually operated valve to cut out the air feed of the by-pass, the manually operated valve operating in conjunction with the usual choker valve mounted in the air inlet of the carburetor.

One `of the principle features of the invention is the provision of means to feed auxiliary air to the carburetor posterior of the liquid fuel feed thereto or posterior of the throttle to form a fuel mixture'for economy at a certain range of part load or part throttle speeds of the internal combustion engine to which the carburetor is attached.

I have found in practice that by having the supply of auxiliary air under the control of the throttle or movement of the throttle so that the throttle is the controlling factor certain new and useful results can beobtained, as the throttle movement controls. the entrance of air which is fed posterior of the throttle to dilute the mixture for economy.

It has been found that to get maximum power from a motorat wide open throttle, the mixture must be of a ratio somethinglike 12-1, or twelve parts of air to one of liquid fuel, by weight, but that for best economy, say ordinary running where the throttle is only partly opened, this ratio can be as much as 16-1, or much leaner, leaving more air in the mixture, and that in order to do this the means must comprise the throttle itself or movement of same, so that such function is under control of the throttle and shall occur during a certain part of throttle range. 'I'herefore, when a carburetor gives the 12-1 ratio of mixture at all speeds, regardless of throttle position, it is not an economical carburetor; neither vis the carburetor that is set to give the leaner mixture of 16-1 the most powerful at all speeds regardless of throttle'position, as the motor which it supplies will be lacking in power at wide open throttle. This leaner mixture of ,16-1, however,

will prove too lean when warming up a cold motor;

the richer mixture -of 12-1 .will prove better for this purpose, and I employ means whereby at the will of the operator the mixture can be changed from this leaner mixture that is good when the cold motor, especially in cold weather, an abnormally rich mixture is had by means, as a rule, of a so-called choker valve by means of which all, or nearly all, of the air is shut off from the carburetor intake. Mymeans to utilize the mixture richer than no-rmal for warming, is associated with the operation of this carburetor air intake choker valve and follows the starting of the motor, as a rule, but in moderate weather the control of this mixture may be such'that it is suflicient of itself to start a motor, and the carburetor main choke need not be used at al1.

It is understood that the mixture ratios given are only examples, but in practice are found to be near the desired mixtures.

It is also a fact that in a so-called plain tube or Venturi type of carburetor, the larger the venturi the less restriction to the air flow and consequently the more power had. from the motor. Where, however, performanceis desired at lowest speeds wide open throttle, one is limited in size of the venturi, for if made too large it will limit the low wide open throttle speed unduly, or in .other words, the venturi will be solarge that the air ow will be too free at low speeds, wide open throttle, so that the vacuum on the fuel jet is unsumcierit to draw the proper quota of fuel from it, making the mixture too lean. I use a venturi of a size somewhat smaller than that required to get the proper maximum power at full speed, wide open throttle, and admit auxiliary air to mixture, this auxiliary air being under control of a valve, calibrated in this case as to weight to lift at a predetermined speed, or vacuum, and feed auxiliary air at the higher speeds to compensate for the smaller venturi, so that it is closed at the lowest range of wide open throttle running, giving suflicient suction on the fuel jet for power, which usually requires a mixture somewhat richer in fuel at the lower range of Vwide open throttle speeds than at the higher range, needing a somewhat slower burning mixture at the lower speed y range. I I therefore use a venturi of very nearly the maximum required size, adding to this auxillary air at all but the lowest range of wide open throttle speeds. y

The structure of the carburetor is just the vreverse ofycarburetors usin'g an auxiliary air inlet, since it has a large venturi at what may be called the primary air inlet, into which the fuel discharges, and a small air valve at the auxiliary air inlet, and the auxiliary air valve remains closed at a low range of wide open throttle speeds, say from 150 to 400, starts to open about 450 revolutins, is wide open at 60o to 800 up, whereas the inlet, and a large auxiliary air valve that begins to open at the lowest speed wide open throttle and continues to open throughout the speed l range, reaching its maximum opening around the maximum speed. By my combination of sizes of venturi and auxiliary air valve, I get the required maximum power at high speed full throttle, and the required fuel feed at the lowest range of speed wide open, so that the performance is better.

Then by combining the control of this auxiliary air with the part open throttle running I get economy; then by the combination of means to shut oil the auxiliary air and render it inoperative, to give an economical mixture, I get the richer power mixture for warming up a cold motor after it is started by an abnormally rich mixture by choking the main air intake.

Other and further objects and advantages of the invention will be hereinafter set forth and the novel features thereof defined by the ap-l pended claims.

In the drawings,

Figure 1 is a side elevation of a carburetor showing the means for controlling the feed of auxiliary air and the main air thereto from a dash controlled member; i Y

Figure 2 is a vertical section through a carburetor constructed in accordance with my invention;

Figure 3 is a section taken on line 3-3 of Fig,- ure 2;

Figure 4 is a section taken on line 4-4 of Figure 2;

Figure 5 is a detail enlarged section showing the throttle valve in part open position cooperating with the lip of the Venturi tube;

Figure 6 is a detail vertical section showing the suction operated valve of the by pass p rovided with a dash pot controlling the movement of the same;

Figure I is a detail vertical section through a slightly modified form in which the by-pass receives its air from the atmosphere;

Figure 8 is a detail elevation of a construction similar to that shown in Figure 'I with the exception that the valve chamber and portion of the by-pass is formed as a separate element and attached to the body of the carburetor;

Figure 9 is a vertical section through still another modif'led form showing the by-pass extending above the throttle valve when in closed position and the use of an additional valve in the by-pass is controlled by the movement of the throttle;

Figure 10 is a section taken on' line III-Ill of Figure 9; and

Figure 1-1 is a section taken on line II-II of Figure 9. a

In the embodiment of my invention as shown in Figures 1, 2, 3, 4 and 5, I indicates the body of the carburetor having a mixing chamber 2 provided with a main air inlet 3 in which is mounted a choke valve 4 carried by shaft 5 extending transversely therethrough to one end of which is secured a collar B provided with oppositely disposed arms 1 and 8. A spring 9 connects the arm 1 to the body of the carburetor for normally holding the choke valve in open position, the movement of which is limited by a pin I arranged in the path of travel of the arm 3 as clearly shown in Figure 1.

Extending transversely through the mixing chamber 2 is a throttle shaft II in which is secured a throttle valve I2 having a lip I3 cooperating with idling ports as will be later described. A collar I4 is secured on one end of the shaft II having anarm I to which is connected an operating rod I6 controlled in the usual manner by the operator of a motor vehicle, suitable stops being arranged to limit the movement of the throttle valve in order to hold it in proper position.

Arranged in the lower end of the mixing chamber is a Venturi tube I1 having a lip I8 formed on its upper end adjacent to where the throttle valve swings for the purpose of filling the space between the wall and the edge of the throttle to get a more ecient air flow from the by-pass l5 into the mixing chamber posterior of the throttle as will be hereinafter more fully described.

The body of the carburetor is provided with a by-pass that leads auxiliary air from the main air intake 3 to the mixing chamber 2 posterior of 20 the throttle valve and is provided with a valve chamber I9 having a removable plug 20 provided with a bore 2l forming a guide for the valve stem 23 of a suction operated air valve 22 which cooperates with a valve seat 24 so as to close the 25 by-pass. The valve 22 is calibrated as to weight so as to lift from its seat at a slight predetermined pressure and open wide at a g'iven pressure, or it can be spring opposed if desired.

The outlet of the by-pass is oblong in shape, having a horizontal length several times greater than its height so as to admit the proper amount of air in a given travel of the throttle valve` to obtain the proper result in the allotted travel of the throttle for economy as about one-third throttle opening will run a motor vehicle miles per hour," the approximate limit range of speed for economy, after which the mixture begins to get richer again until at wide open throttle the mixture is for power. The upper edge of the by- 40 pass is rounded as shown at 25 and the edge of the throttle valve is rounded as shown at I2' to prevent undue noise when the air enters the mixing chamber above throttle.

Arranged within the by-pass below the suction valve .22 is a manually operated air valve 26 for controlling the passage of auxiliary air therethrough. The valve is mounted on a valve stem 21 extending transversely through the walls of the by-pass and has xed on one end a collar 5" 2B provided with an varm 29, the movement of which is limited by a pin 29 as shown in Figure 1. The arm 29 is provided with an opening through which passes a rod 30 having an adjustable collar 3| fixed thereon. A spring 32 sur- 5" rounds the rod between the collar 3I and arm 29 of sulcient stiffness to transmit motion to arm 29 to close the auxiliary air valve 26. 'I he rod 30 is provided with an adjustable collar 32 spaced from the arm 29 and adapted to engage the same 6 for opening the auxiliary air valve. The rod 30 is connected to a choke operating rod 33 as shown i at 30' which extends to the dash 333 of the motor vehicle. The arm 3 lis provided with an opening through which the lower end of the rod 33 6" ypasses as shown in Figure 1 and has fixed thereon an adjustable collar 34 so that when the rod 33 is drawn upwardly, the collar will engage the arm 8 and close the choke valve. When the rod 33 is operated, the air valve 23 70 is moved until it engages the wall of the by-pass and further movement of the rod 33 compresses the spring `32 to allow lost motion so that the rod 33 can continue to move and close the choke valve. The rod 33 is provided with angular` por- 75 tions 33' and 332 cooperating with the opening in the dash to hold it in its adjusted positions when the rod is pulled until the portion 33' cooperates with the dash and the choke valveand auxiliary air valve -of the by-pass are in closed position for starting.

After the engine is started, the rod 33 is pushed in until the dash is engaged by the shoulder 33 which opens the choke valve, but the air valve and by-pass remain closed. After the motor has obtained the proper temperature. the rod is pushed all the way in to allow air to be fed through the by-pass to the mixing chamber of the carburetor. The body of the carburetor has preferably formed integral therewith a constant level fuel chamber 35 having the usual float controlled needle valve for controlling the supply of fuel thereto. The fuel bowl is provided with a restricted outlet 36 which communicates with a fuel passage 31 terminating in a vertically disposed nozzle 38, the end of which terminates within the restricted portion of the Venturi tube |1. This restriction may be in the `form of a calibrated plug or needle valve so as to calibrate the ow of fuel from the fuel chamber to the nozzle of the carburetor. Extending upwardly through the wall of. the body of the carburetor from the fuel passage 31 is an idling passage 39 having a calibrated jet 40 at its upper end. This fuel jet extends into a continuation of an idling passage 4| which is provided with an air inlet 42 so that the fuel from the passage 39 and `iet 40 is mixed with some air at this point.

Disposed in the body of the carburetor'between the idling passage 33 and the fuel bowl is an auxiliary reservoir 43 for pick-up purposes as is commonly understood in the art, said auxiliary reservoir being provided with a vent 44 to the atmosphere to allow the same to empty into and out of the-nozzle 38.

The idling passage 4I is provided with a valve controlled air inlet 45 controlled by an adjusting screw 46 for making the final adjustment of the fuel mixture discharging from the idling passage above the throttle during idling or closed throttle position. The idling passage 4| terminates in ports 41 and 48, the port 48 being arranged above the lip of the throttle when closed and the port 41 being closed by the lip of the throttle so that when the throtte starts to open, the fuel feed is augmented by added fuel from 41. The conystruction of the idling passage is substantially the same as shown in a companion application hereinafterv referred to, but I have found that it is important that a similar idling and transfer device be used in combination-where the opposite edge of the throttle valve controls the admission of auxiliary air through the by-pass for economy and while I have not specifically described the various features of this idling passage, the description is suflicient for anyone skilled in the art to clearly understand the operation of the same in view of my companion application pending in the United States Patent Oiilce, led March 3, 1928, Serial Number 258,738 and which has matured into Patent No. 1,838,675, Dec. 29, 1931.

In the embodiment of my invention as shown in Figure 6, the suction operated air valve 22' isprovlded with a stem 23' working in a bore or chamber 2|f formed in the plug 2li'V in order to form a dash pot for the movement of the suction operated air valve in order to prevent the too sudden opening of the air valve as the stem in connection' with the bore or chamber forms valve 63 in the by-pas's.

an air cushion ofy the entrapped air to produce a dash pot for retarding the movement thereof. In the embodiment of my invention as shown in Figure 7, a construction is illustrated substany tially the same as shown vin Figures 1 to 5 with 5 the exception that the lower end 50 of the bypass is in communication with the atmosphere and the auxiliary air is fed from the atmosphere instead of through the intake of the carburetor. In the embodiment of my invention as shown in Figure 8, a construction is lillustrated substantially the'same as show'n in Figure 7 with the exception that the by-pass and valve chamber is formed as a unit 5| and is attached to the body of the carburetor. l5 In the embodiment of my invention as shown in Figures 9, 10 and l1, 52 indicatesv ,the body of the carburetor which is provided with a mixing chamber having a venturi 53, main air intake 54 and a nozzle 55 extending into the same. 20 The float chamber and fuel supply are not shown in these figures, but the body is constructed substantially as shown in Figures l to 5 and a suitable idling passage 56 is provided for feeding fuel above the throttle for idling purposes.

Extending transversely through the mixing chamber is a throttle shaft 51 carrying a throttle valve 5B operated in the usual manner and having-an arm 59 carried thereby which carries a rod 60 extending through an arm 6| carried 30 by a valve stem 62 of a valve 63 mounted in the outlet of a by-pass which communicates with the main air intake in a similar manner as shown in Figure 1 and is providedwith a suction operated valve 64 and a manually operated 35 valve 65 operating in substantially the same manner as shown in the preferred embodiment of my invention.

A suitable choke valve 66 is disposed within the air intake and has an arm 61 provided with 40,

an opening through which the operating rod 68 passes, which also passes through an arm 69 carried by the valve stem of the Valve 65, a suitable spring being disposed on the rod and cooperating with the arm at one end and with an adjust- 451 able collar at the other end so as to provide a lost motion between the movement of the choke valve and auxiliary air valve; whereby these valves will operate in substantially the same manner as previously described so that when one 50' valve is open, the other is opened and when one valve is closed, the other is closed, a lost motion being. obtainedk between the movement of the two valves so as to permit valve 65 to remain closed after the choke' valve 66 has movedinto 55 open position until a nal adjustment of the rod has been obtained.

The rod 60 is surrounded by a coil spring 10 YVwhich engages the arm 5| at one end and an adjustable collar 1| at its opposite end so that 00 there is a lost motion between the movement of the throttle valve and the movement of the air In this construction, the auxiliary by-pass for air enters the mixing chamber of the carburetor posterior of the throt- 05 tle when closed and the movement of the valve 63 is controlled by the movement ofthe throttle valve so as to close and open -the auxiliary air by-pass by the movement of the throttle so as .to' control the admission of air in substantially 70 the same manner as in tmf-preferred embodiment of my invention. l From the foregoing description it will be seen that I have provided a carburetor with means for feeding auxiliaryair to the' mixing chamber 75 of the carburetor posterior to the fuel nozzle, which auxiliary feed of air is under the control of the operator directly or indirectly by the movement of the throttle valve.

In the operationof a carburetor constructed in accordance with my invention, assuming that the constant level fuel chamber is in communication with a source of supply amd that the fuel therein is maintained at a predetermined level, the choker rod 33 is pulled out until the shoulder 33' engages the dash which closes the choker valve 4 and the auxiliary by-pass valve 28. In this position of the valves no air can enter the main air inlet or the by-pass whether it is connected with or not connected with the main air intake of the carburetor. This subjects the noz- Azle to an excessive suction giving a rich fuel mixture for starting. After the engine to which the carburetor is attached is started, the rod 33 is pushed into the position shown in Figure 1 which opens or allows the spring-actuated choker valve 4 to move into open position and the bypass valve to remain in closed position, it, of course, being understood that the throttle valve of the carburetor is in partly open position which gives a richer mixture than normal running part throttle. After the motor has been heated up so that the desired temperature condition has been reached, the operating rod 33 is pushed all the way in, the movement of which opens the air valve 26 in the by-pass, thus allowing air from' the by-pass to be fed to the mixing chamber of the carburetor and when the throttle is operating in the range of the heighth of the by-pass outlet, the greatest economy can be obtained. As the greatest part of the auxiliary air goes posterior of the throttle Where the sucit will have a greater Width than height since this range only extends about one-quarter to onethird of the throttle travel for economy range. As soon as the throttle is in position to allow air to flow from the by-pass posterior of the throttle, the suction operated air valve will lift, allowing air to flow thereby. The purpose of the suction operated air valve is to close the by-pass at the lowest speeds, wide open throttle, when there is little suction or vacuum on 'the nozzle of the carburetor so that by closing the by-pass by the suction operated valve, more suctiori is obtained on the nozzle of the carburetor, thereby getting more fuel at low.speed than when the by-pass is opened.

When the suction operated valve is lifted, which it will be at say 400-600 revolutions, it offers no restriction to the air flow through the by-pass and thus gives a greater weight of mixture at the highest speed than would'be the result if the by-pass was closed. At the low speeds, the venturi is ample in itself to feed the maximum amount of air as the piston speed is slow and the time element is pronounced when it comes to feeding a certain weight of air.

The area of the by-pass is usually made about 20 to 25 per cent of the area of the venturi or the smallest restriction thereof. The size of the restriction from the constant level fuel chamber is so calibrated that at maximum speed, wide open'throttle, the most powerful mixture is obtained 12-1 and at the lowest speed, wide open, say 200 revolutions per minute, the suction operated valve being closed, the mixture may be alittle richer than 12-1 or at least that rich. While the lower lip of the throttle is operating within the range of the by-pass outlet, auxiliary air from the by-pass will mainly feed posterior of the 5 throttle and iiow at a high velocity due to the greater vacuum or suction effect posterior of the throttle, thus diluting the mixture which is calibrated for economy, about 16-1 ratio.

In the construction of carburetor as herein l0 shown, I am able to use a small venturi and by having the auxiliary air inlet oblong in shape or of a greater width than height, the proper amount of air will be fed to the carburetor when it is desired and with the use of a suction operl5 ated valve I compensate for the small venturi as this valve lifts at high speed to supply the additional amount of air required to form the proper combustion mixture. In constructing the air inlet, I form the upper edge rounded adjacent 20 the throttle edge so that this air is fed posterior of the throttle vwhereby a carburetor is produced having a small Venturi tube in combination with4 an auxiliary air inlet so constructed that the combined feeds are equal to a larger venturi 25 whereby I am able to supply the charge forming device withthe proper amount of air at high speed.

It will also be seen that I have provided a novel construction of air inlet combined with a small 30 Venturi tube and so arranged in respect to the throttle that in the opening movement of the throttle and at the proper time the proper amount of air will be supplied to compensate for the smaller Venturi tube. 35

From the foregoing description it will be seen that I have provided a carburetor having a main carbureting passage provided with an air inlet in which a venturi is disposed having a lip cooperating with the edge of an oscillating throttle 40 which in turn controls the entrance of auxiliary air through an elongated opening, said auxiliary' air passage having a suction controlled valve which opens at the proper time so as to compensate for the small size of Venturi tube used, 45 said auxiliary air passage being provided with a manually operated means so as to completely close the passage and prevent the passage of air therethrough to the main carbureting passage, said valve being connected through lost motion con- 50 nections with the main air choke valve of the air inlet of the carbureting passage, whereby I am able to control these various valves in order to produce an abnormally rich mixture for starting, the proper mixture for normal running and 55 to reduce the richness of the mixture at the proper time for economy.

What I claim is: n

V1. A carburetor for internal combustion engines having amixing chamber, a fuel chamber G0 having an outlet for feeding fuel thereto, a main air inlet for said mixing chamber for feeding the major portion of air thereto, an auxiliary air inlet to said mixing chamber in communication with the main air inlet, and through which 65 only air passes, a `suction operated valve controlling the ow of air through said auxiliary air inlet, a throttle valve lmounted in said mixing chamber and arranged so that the throttle valve in closing passes between the outlet of the aux- 7o iliary air passage and the engine, said valve being mounted to remain closed during the lowest speed range of the engine and wide open before, and during the maximum speed range of the engine. 75

2. A carburetor having a mixing chamber, means for feeding fuel and air thereto, an oscillating throttle valve mounted therein, an auxiliary air admitting means controlled by one edge of said throttle valve to dilute the fuel mixture, said throttle edge opening away from the outlet of said mixing chamber and means for feeding additional fuel to said mixing chamber before the main fuel, feeding means starts to operate controlled by the opposite edge of said throttle valve and a suction operated valve mounted in said auxiliary air admitting means.

3. A carburetor comprising a body having a carbureting passage provided with a main air inlet, means for supplying fuel to said passage, an oscillating butterily throttle valve mounted in said passage, an auxiliary air passage in communication with said main air passage and arranged so it discharges the greatest volume of its air to the carburetorl passage posterior of the throttle when the throttle is partly open, the

said throttle in its movement being adapted to sweep past the discharge opening of said auxiliary air passage, a manually controlled valve in said'auxiliary air passage, a manually controlled valve in said main air passage and a connection between said valves.

4. A charge forming device for internal combustion engines comprising a carbureting passage having a throttle for controlling the feed of fuel mixture to said engine, means for feeding fuel thereto, a main air inlet for said carbureting passage, an auxiliary air inlet for said passage in communication with the main air inlet passage and over which the throttle valve sweeps, a

, valve in said main air inlet passage, a valve in said auxiliary air inlet, a lost motion connection between said valves and manually operated means for controlling the connection between saidvalves to allow one of said valves to remain open when the other is closed.

5. A charge forming device for internal combustion engines comprising a. carbureting passage having a throttle for controlling the feed of fuel mixture to said engine, means for feeding fuel thereto, a main air inlet for said carbureting passage, an auxiliary air inlet for said passage which receives its air from the main air inlet passage and over which the throttle valve sweeps and so arranged that the throttle valve when closing passes between the outlet of theauxiliary air passage and the engine, a valve in said main air inlet, a valve in said auxiliary air inlet, a lost motion connection between said valves and manually controlled means for said valves, the initial movement of said means closing said auxiliary air valve and the nalmvement the main air valve.

` 6. A carburetor for internal combustion engines comprising a body having a mixing chamber provided with a normally open air inlet, a 5 butterfly throttle valve mounted in said mixing chamber, means for feeding fuel to said mixing chamber to form the. maximum richness of mixture for maximum speed of the engine, means controlled by the throttle for decreasing the richness of said mixture by feeding auxiliary air posterior of said throttle valve, a suction operated valve in the passage Ifor feeding auxiliary air and means for rendering the last mentioned means ineiective when the throttle is partly open and the air inlet is open, the said throttle, in its movement sweeping past Athe discharge opening of the means for decreasing the richness of the mixture. n 7. A carburetor comprising a .body provided with a mixing chamber having a normally open main air inlet, a throttle valve in said mixing chamber, means for feeding fuel to said mixing chamber to form a normal fuel mixture, manually operated means for controlling the admission of air through said air inlet for increasing the richness of said mixture, means controlled by the throttle for admitting auxiliary air to said chamber posterior of said throttle valve to decrease the richness of said mixture and means operable by `said manually controlled means for rendering said throttle control means ineiective when said throttle is in partly open position and the main air inlet is open.y

8. A carburetor comprising a body having a mixing chamber provided with a main and an auxiliary air inlet, said mixing chamber having a venturi mounted therein provided with a lip in alignment with the auxiliary air inlet, and an oscillating throttle valve mounted in said mixing chamber cooperating with said lip to deflect entering air posterior of throttle.

9. A carburetor having a mixing chamber provided with an air inlet, means for feeding fuel to said mixing chamber, an oscillating throttle v valve mounted therein, an auxiliary air inlet adjacent the edge of said throttle Valve having a width greater than its height and, provided with a rounded upper edge cooperating with the edge of the throttle valve for decreasing the richness of the mixture and means to render the auxiliary air inlet ineiective when the motor 1 is being as FRANK H. 

